This invention relates in general to a shuttleless loom of the type having a weft catching arrangement in which a plurality of weft catching yarns successively catch inserted weft yarns while being drawn at a required rate, and more particularly to an apparatus for detecting malfunction on drawing of the weft catching yarns in such weft catching arrangement.
As is well known in the art and is described to some extent in U.S. Pat. No. 3,297,057, a shuttleless loom, for example, of a fluid jet type is provided with a weft catching arrangement which comprises a plurality of weft catching yarns (hereinafter referred to as "catch yarns" for brevity) disposed in tensioned state on one side of a warp array. The catch yarns are adapted to form a shed like the shed formed in warp yarns and to be collected for grasping an inserted weft yarn by beating operation. In order to insure that the end portion of the inserted weft yarn is firmly grasped by the catch yarns and to tension the inserted weft yarn, the weft catching arrangement is provided with a twisting device for twisting the catch yarns having grasped the inserted weft yarn. The catch yarns are further adapted to be drawn at a rate equal to or larger than the rate at which the woven fabric moves toward a cloth roller, retaining the end portions of the inserted weft yarns even after they have been severed from the edge of the woven fabric. In order to draw the catch yarns as above, the weft catching arrangement of an ordinary type is provided with a catch yarn drawing device of the type which includes a pair of cooperative rotatable members such as spur gears or rollers, which nip therebetween the catch yarns and draw same by rotation thereof. The catch yarns having passed the catch yarn drawing device are then led downwardly by their gravity to some accumulating device or wound on a reel.
Although the catch yarns are arranged to be drawn as above, it happens that the catch are wound on one of the rotary members. This is caused by the fact that the filament or fibre consituting a catch yarn or a weft yarn is caught by some chipping or cutting marks on the peripheries of the rotary members or stuck in some sizing starch existing on same. As the catch yarns are wound on one rotary member, the catch yarn drawing rate increases gradually since the length of the catch yarns having wound effects the increases in the diameter of the rotary member. Such increase in the catch yarn drawing rate leads to imperfect weaving operation of the loom and finally to the breakage of the catch yarns.
The breakage of the catch yarns also happens for the cause of malfunction in the twisting device. For example, during twisting of the catch yarns by the twisting device, it happens, though on rare occasions, that one of the weft end portions retained by the catch yarns is tangled with some element of the twisting device to cause the breakage of the catch yarns.
Since the breakage of the catch yarns causes fatal disadvantages in weaving operation of the loom, it is desirable to give notice of the breakage to the operator of the loom so that the operator can repair or reset in order the catch yarns as early as possible, and it is more desirable to give notice of malfunction on drawing of the catch yarns to the operator before the catch yarns are broken so that the operator can reset the catch yarns in order through a simple resetting work and therefore a shorter resetting time.